Adjustable length tail pipe for oil field operations



April 5 1960 G. D. 'rHoMPsoN 2,931,438

ADJUSTABLE LENGTH TAIL PIPE FOR OIL FIELD OPERATIONS Filed Nov. 21, 1957 c "sLlPs sErL INVENTOR.

GENE D.l THOMPSON,

ATTORNEY.

ADJUSTABLE LENGTH TAIL PIPE FOR OIL FIELD OPERATIONS Gene D. Thompson, Houston, Tex., assigner, by mesne assignments, to Jersey Production Research 'Sompau Tulsa, kla., a corporation of Delaware Application November 21, 1957, Serial No. 697,987

` 1 Claim. (Cl. 166-138) This invention relates generally to apparatus for use in oil field operations, and more particularly to a variable length tail pipe or anchor pipe for use in conjunction with a well packer.

A conventional type of well packer includes an expansible, compressible, generally cylindrical member of rubber or rubber-like material connecting together two sections of pipe, the upper section of which may be a drilling string. The lowermost section of pipe may be adapted to abut against the bottom of a drill hole or to be supported by another packer or by sidewall anchoring means, so that when pressure is applied to the expansible, compressible member from the earths surface or by the weight of the drill string through the other section of well pipe connected thereto, the member will expand to contact the side of the borehole with considerable force and electively seal olf a section vof the borehole. The packer may be used in many operations, a common operation being drill stem testing; lluid entering the borehole beneath the packer can go to the earths surface only through the pipe so that workmen at the earths surface can obtain earths fluids from the strata penetrated by the borehole.

In the course of setting the packer, often it is found impossible to obtain an effective seal using a given length of tail pipe. Therefore, it becomes necessary to vary the length of the tail pipe so that another attempt to obtain an effective seal may be made. Manifestly, it is undesirable to bring the packer to the earths surface to connect a tail pipe of diierent length to the packer, or to adjust the length of the pipe connected to the packer by manual manipulations performed with the packer and tail pipe at the earths surface.

In accordance with the teachings of the present invention, a pair of telescoping tail pipe sections areconnected to the lower end of a flexible, expansible well packer. The position of the lower section is xed within the borehole. In combination with the telescopic tail pipe sections, there is provided connecting means for selectively connecting and disconnecting the tail pipe sections responsive to manipulations ofthe drilling string fromrthe earths surface. Preferably, the manipulations a're limited to raising, lowering, and rotating the drilling string, well packer, and the uppermost of the telescoping tail pipe sections. j l

' A preferred embodiment of the invention utilizes a slip cage between the telescoping tail pipe members longitudinally movable with respect to the tail pipe members and carrying slips which are adapted to ride ou an inclined surface of one of the tail pipe sections to engage the other tail pipe section and establish a strong mechanical 'connection between the two sections. Preferably, the mechanical connection between vthe tail pipe sections is established by the operation of setting down on `the packer. The slips should be disengageable by picking up the drill string to disconnect the two tail pipe sections, to permit relative longitudinal movement Patented Apr. 5, 1960 length of the tail pipe when the packer is again reset.

A more complete understanding of the invention may be had from the following description thereof when considered with the accompanying drawings wherein:

Figs. 1, 2, `and 3 are elevational views, partially in cross section, of a preferred embodiment of the invention in various successive operating positions thereof, and

Fig. 4 is a view of a portion of the inner of the telescoping tail pipe sections illustrating a slot therein which serves to actuate the slip cage shown in Figs. 1, 2, and 3.

With reference now to Fig. 1, there is shown a packer and tail pipe assembly with the various components thereof in the positions that they will assume as they are being lowered into the borehole 2. Packer 3 may be a set-down packer as shown in U.S. Patent 2,661,064 to J. Rockoff. 'Ihe packer itself may be constructed of steel-braid reinforced rubber or rubber-like material, adapted to expand outwardly toward the sides of the borehole when a compressive force is exerted between the ends of the packer.

Retaining collars or shoes 13 and 14 couple the ends of the packer to cylindrical pipe sections 1 and 4. Pipe section 1 may be connected to a drilling string in the usual manner. Mandrel 4 is one member of a telescoping tail pipe or anchor pipe assembly, the other telescoping section being identified by numerals 5 and' 7. The end portions 5 of the outer or lower tail pipe member permits insertion of the slip cage within the lower tail pipe member. O-ring 6 provides a seal between mandrel 4 and end portions 5. Outer tail pipe portions 5 and 7 are screw-threaded together as shown.

The lower end of outer tail pipe member 7 has a plurality of openings therein to permit free uid communication between the borehole and the interior of chamber 35 when the tail pipe abuts against the bottom of the borehole or is anchored to the sidewall above the bottom of the borehole by suitable sidewall anchoring means. In this manner, formation fluids from the borehole may freely enter the interior of pipe section 4. A small orice 24 prevents the build-up of a differential pressure between chamber 33 and the borehole that could rupture tail pipe member 7. Chamber 33 may be loaded with fluid to exclude drilling mud from the chamber as much as possible. v

To rigidly connect the tail pipe sections 4 and 7 together, there is provided a slip cage assembly adapted to connect and disconnect sections 4 and 7 responsive to vertical manipulation ofv the drilling string. The slip cage assembly, which includes sections 15, 16, and 18, supports a plurality of slips 9. The slips 9 are adapted to ride up on a setting cone 8 so as to expand outwardly to engage the inner surface of chamber 33. Setting cone 8 may be a portion of tail pipe section 4 or it'may be` a separate member friction tted or otherwise securely afxed to tail pipe section 4 (for example, by a welding operation). Slip cage sections 15, 16, and 18 are annular members adapted to fit around the lower end of tail pipe section 4 between setting cone 8 and lugs 23. Section 16 is positioned bet-Ween sections 15 and 18 and carries a pin 12 adapted to engage a slot 20 Within the tail pipe section or mandrel 4. The shape of groove 20 is. illustrated more perspicuously in Fig. 4, and its function@ will become apparent from the following discussion.

Slip cage sections 15 and 18 are connected together i by a plurality of drag springs 11 which bow outwardly provided which should exert suicient force against the walls of chamber 33 to prevent free downward movement,

' message of th e slip cage responsive to gravitational force. An external force to reposition the slip cage may be applied through the packer and mandrel 4 by manipulation of the drillstring.

Slip cage-section 16 Ais freely rotatable andindependentofthe othersections 15 and 18;

A While slips 9 are shown Aas being aiiixeditorupper slipl vcage section 15, it is to be understood thatV they may be connected to the lower slip cage section- 18, if` de siredl The operation of the apparatus shown in the drawings as follows: Let it be assumed that the packer andy tail pipe assembly are'being lowered intothe borehole. The pin 12 should be in position A- ofY Fig. 4. In this position the tail-pipe section7 will be. suspended from or hanging on the-'uppersu'rfaceY of setting cone 8. The assembly is lowered'into the .boreholeuntil' thelower end.. of lower tail pipe member 7- touches'the bottom.v Thel drill string,'packer 3, and mandrel14 are lowered further until the lugs 23` on mandrel 4Y strike the seal. ring shoulder' or wall 25. This will assure the operatorV at the earths surface that the assembly is a't the bottom of the" borehole. Nbte that the pin 12' isstill in posi- After the lugs 23 strike the seal ringY shoulder 25, the drill string 1, packer 3, and mandrelV 4` are raised; Pin

is.` cammed horizontally by the'edg'eof4 groove 20 torotate section '116. lin l2 will move along' th'e groove until it is in position' B (see Fig. 4).- When-pin" 12 is in this position, the slip cagewill be raised wlennthe'l uppertailY pipe 'section'v 7` andl the pipe string are raised, until the packer is above theV position' at which it is to be set bvV a distance equal to the distance between' pointsV B' and The drill string; packer 3, and` mandrel 4"'arethen lowered. The slip" cage assembly'willf on groove 2d' (Figi 4).

riot move downwardly due to the restraining inuence of drag springs 11'. Pin 12 will move through slot 20` from position B towardV position C until the slips engageY conical'surface 10 of setting con'e8. VTh'e' slipswillY bey biased'outwardly by conical surface 10' until theyV engage the=inner surface of chamber 33. Pin 12'will then be in position C as shownv in Fig. 4. At this point, downward' forcel may be exerted from the drill stringi which will force the slips to dig or bite into the wall of chamber 33` (see Fig'. 3)l so that there is a rigid mechanicalconnec# tion' between mandrel 4 and tail pipe sectionV 7. TheV packer" may now be set by application'of more force" thereto.

Ify the packer does not engage the side of theborehole so as to sealoff the lower portion of the borehole, the" drill string is picked up. As the drill string'is raised,

the packer is` released to assume its normal shape, asI shown'in Figs. l and 2. The settingV cone 8 is raised outV of engagement with the slips and the slips' should collapseto the position shown in'Fig; l. 4i moves up, the pin Vwill move y.downwardly and willl change from position C to position D, as shown in Fig. 4.

- ".Whven'the pin reaches position D,the vslip cage will be- A's the mandrel vide fluid communication between the interior of said.

4 It is tobe noted that pin 12`can move in onlyone direction through the slot 20 in mandrel 4. The direction of movement is shown by the arrows in Fig. 4 and will follow the sequence of positions A, B, C,Y D, A. The shape of the slot is substantially the same as that of the slotted section in the so-called Knowlton packer manufactured by Knowlton Oil Tool CompanyLosAngeles, California.

The invention described above permits a'packer to be reset any number of Vtimes without the necessity of a; round trip ofthe packer fromV theborehole to the surface. The operation for resetting the packer can be performed Vby workmen at the earths surface almost entirely by raising and lowering' thev drill string; The' apparatusl as described is rugged, almost foolproof, and almost entirely kvoid ofV maintenance problems.

The invention is not to be restricted to the specific structural details orarrangements ofpartsfras various modilications thereof may be effected without departing fromthe spirit-and scope of this invention.y Y

I claim: Y In combination: a-pipe string; a well packer including an expansible well` packingmember aixed'to theflower endof saidpipev string, said packing member being adaptedto expand to the sides of aborehole responsive to longitudinal pressure exerted on said pipe string; a` tailv pipe for holding said packing member aboveA the bottom of saidborehole, vsaidtail pipeincluding a lirst inner hol,-v low, elongated tubular telescoping memberconnected to saidV` packing member andV a secondV hollow, elongated` tubular telescoping member in telescopin'g'engagement ing member being adapted tov abuty against the bottomfof the borehole;- a wall within said second telescoping mem'- ber defining an elongated chamber therein, said first tele-4 scoping member extending longitudinally through said: second telescoping member andV through said wallto'prolar member being rotatable about said first telescoping member; aplurality of drag springs connecting togethersaid iii-st and third annular members, said drag springsv being adapted to bias Vagainst the sidesof the interior of said second telescopingmember to restrainl movement of said slip carriagev responsive to gravity; al plurality ofslips affixedv to saidV slip carriage; a conicalI slip setting member aixed'to said first telescoping member, said' slip'i setting member being adapted to force saidV slips against y theinterior of.V said second telescoping. member to Vrigidly' connect together said lirst and second Vtelescoping mem-v positionl The mandrel 4 can nowv either be raised or lowered to lengthen or shorten the overall length of the tail pipe. lf itis desired toV raise the mandrel, for example, into the position shown in Fig.V 2, the pin 12 will r'emain in position D. However, if it is desiredto lower the'V mandrel, pin 12 will move again to position A and the' slip cage will downwardly' untilY itv reaches' theYV next' position at-'wiiich it desired to try vtoi se't the packer.

Whenftli'eiV slipY cage is in its new position,v the drilling" s't'iing' andpacke'r are'lifted so that pin 12 willV move* into' ps'iticiiiA Bfan'd' theny the drill string v and packer are` lower'ed so that theA pin* is moved to positionC Vto expandv Y die? slips andv` set!v the packer' as* described above'.

bers; a slot in' said first telescoping member defining a'. closed path, a pin in said secondfannular member ii'tting;v into said slot, said pin. beingadapted to move in a given` direction around' said path to successively move sadslipV carriagey downwardly relative tosaidsecond telescoping member, to move said-slip carriage upwardly relativeto* said'second telescoping member, to move said slips into engagement withsaid slip setting member, and-tol disen-l gage vsaid slips frornsaid slipsettingmember.Y

References Cited in the leof thispatent v UNITED srATnsn.#murs"A 

